Establish tumor models closely resembling human tumors, use neuraminidase to modify tumor cell surfaces and also to use other glycosidases to determine whether they have any effect on tumor regression and, if so, to establish the dosage and route schedules which will maximize tumor regression activity. Attempt to develop nonviable immunogenic tumor cell or tumor cell fractions from enzyme treated cells in an attempt to develop a safe vaccine for established tumors. Attempt to determine the efficacy of other antitumor therapy on the antitumor immune response induced by neuraminidase treated tumor cells.